for example, a two-step batch leaching test at L/S 100 l/kg with pH fixed in the two steps at 7 and 4 (van der Sloot et al., 1994; Nordtest, 1995; Fa¨llman and Aurell, 1996; Fa¨llman, 1997; Kosson et al., 2002). The availability test aims to determine the fractions of residue constituents that may leach out under extreme conditions, i.e., at low pH and after very long time. The availability test defines ‘‘potential leachability’’ in terms of the specific operational conditions used in the test